Normal Limits

"Chance is the very guide of life"

"In practical medicine the facts are far too few for them to enter into the calculus of probabilities... in applied medicine we are always concerned with the individual" -- S. D. Poisson

October 27, 2005

Molecular Medicine - Molecular Identification of Simian Virus 40 Infection in Healthy Italian Subjects by Birth Cohort (Paracchini et al 2005)

It is not disputed that polio vaccines manufactured from 1954 to 1963 were contaminated with the polyomavirus SV40. However there has been accusations that the vaccine made from monkey kidney cells continue to be in part contaminated, and that the virus is responsible for certain types of cancer (eg malignant mesothelioma) based on animal studies. Epidemiological studies of humans have been inconclusive as a whole. (for a more-than-likley biased review see The Virus and the Vaccine).

Even if current batches of vaccines continue to be potential sources of SV40 contamination, and even if SV40 virus indeed causes cancer in a subset of people infected, an important question had thus far been unanswered--is the vaccine the only potential source of SV40?

This study studies the prevalence of SV40 in donors in Italy who had no known cancer. Using the peripheral blood lymphocytes of 134 solid organ donors (all anonymous) they screened for SV40 using PCR and then confirmed it with DNA sequencing. They found 15 of these (11%) to contain de facto SV40 genome sequences. If indeed the contaminated polio vaccine was capable of infecting its receipients, then we would expect those donors who were born between that period of time would be more likely to be infected with SV40. This was not found to be the case.

One major drawback is the small sample size. But I see this as the beginning of a very important new line of research. At the very least it should settle the SV40-vaccine debate, if not rendering it moot.

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